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This paper describes the design, simulation, fabrication and characterization of micro checkvalves suitable for integration into polymeric microfluidic devices such as micropumps or test cartridges for biomedical analysis. The valves are fabricated by a polymeric surface micromachining process, which utilizes SU-8 as the functional material. The devices are assembled with the lamination technique. A micro checkvalve consists of 3 layers: an inlet layer, a valve layer and an outlet layer. The valve is a disc of 1-mm diameter. The disc is suspended on folded beams, which act as valve springs. Both valve disc and springs are fabricated in a 100-µm SU-8 layer. The valves prove a clear flow rectification function. Relatively low pressure is required for opening the valve. The valves were tested and characterized with water. One of the valves are successfully integrated into a polymeric micropump. These valves prove the facile and reliable lamination technology for fabrication complex polymeric microfluidic devices for biomedical analysis.

This paper presents the first micropumps assembled using polymeric lamination technology. Each pump consists of two 100 µm thick, 10 mm diameter SU-8 discs; two 1.5 mm thick, 15 mm diameter polymethylmethacrylate (PMMA) discs; and one piezo disc. The SU-8 parts were fabricated by a two-mask polymeric surface micromachining process with silicon as the sacrificial material. Each SU-8 disc has one micro check valve. The valve is a 1 mm plate suspended on a compliant orthoplanar spring. The cross section of the spring beam has a dimension of 100 µm × 100 µm. The PMMA parts were machined from an extrusion PMMA sheet by CO 2 laser. An off-the-shelf piezo bimorph disc worked as both actuator and pump membrane. The pump was assembled using adhesive bonding. The adhesive tapes were cut by the same laser system. Alignment pins were used in the assembly process. With a drive voltage of ±150 V the fabricated micropumps have been able to provide flow rates up to 2.9 ml min −1 and back pressures up to 1.6 m of water. The pump design and the polymeric technologies prove the feasibility of making more complex microfluidic systems based on the presented lamination approach.

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